How to Reinforce a Shower Mortar Bed

Use sheet metal cutters with rubber grips when cutting wire lath.

Many professionals consider a mortar bed superior to other systems for tile showers. Mortar beds consist of a layer of building paper, extruded metal lath and cement mortar. While the system is fine for the walls, shower floors on plywood subfloors need additional reinforcement to prevent cracking. A polymer in the mortar combined with stucco lath provides a reliable reinforcement. The lath is designed so mortar flows behind the wire instead of on its surface, as with extruded metal. The lath is installed at the floor after the waterproof membrane, or sub-pan, has been installed.

1

Put on work gloves. Measure the shower floor from side to side and add 16 inches to allow bending up each end of the stucco lath to conform with the corners of the floor and walls at the perimeter. Cut a sheet to length by cutting the paper backing and wires with sheet metal cutters.

2

Place the first sheet flat on the shower floor with the wire facing up and the paper backing underneath. Bend up each end 8 inches so they fit against the walls. Align one edge with one side of the floor.

3

Measure the remaining floor area in the shower. Cut an additional sheet of stucco lath that fills the remaining area and bends up 8 inches at each end. Place the sheet on the floor and bend up each end 8 inches.

4

Attach the sheets of lath with 1 1/4-inch aluminum ring-shank roofing nails. Drive the nails at the wire's intersections along the upper and lower portions of the edges that bend up and at the floor with a hammer.

5

Measure the remaining walls at the perimeter of the floor where lath is not installed and add 8 inches. Make a 4-inch bend at the end of each piece that overlaps onto the installed lath at the perimeter walls. Attach these with nails at 8-inch intervals along the upper and lower edges and the overlapping ends. The floor is ready for a mortar bed after the walls are papered and extruded metal lath installed.

Things You Will Need

Work gloves

Measuring tape

Stucco lath

Sheet metal cutters

1 1/4-inch aluminum ring-shank roofing nails

Tip

Experienced do-it-yourself enthusiasts can staple the stucco lath with a pneumatic stapler and coated steel staples used to install the lath at stucco walls.

About the Author

William Machin began work in construction at the age of 15, while still in high school. In 35 years, he's gained expertise in all phases of residential construction, retrofit and remodeling. His hobbies include horses, motorcycles, road racing and sport fishing. He studied architecture at Taft Junior College.